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Biomedical subjects

M W McDermott

Publications and source records attributed to M W McDermott.

11 recordsLinked to original sources
PubMed1992

A comparison of CT contrast enhancement and BUDR labeling indices in moderately and highly anaplastic astrocytomas of the cerebral hemispheres.

Contrast enhancement on computerized tomography (CT) scans has been used in directing therapy for presumed intracranial gliomas. However, for moderately anaplastic astrocytomas (MOAAS) and highly anaplastic astrocytomas (HAAS), it provides no information about proliferative potential. The bromodeoxyuridine (BUDR) labeling index (LI), however, indicates proliferative potential, correlating with histologic malignancy and survival. An LI less than 1% is a favorable indicator; LI greater than 5% suggests more aggressiveness. To determine the correlation, if any, between BUDR LI and contrast enhancement, CT scans of 71 patients with cerebral hemisphere tumors labeled with BUDR were retrospectively reviewed. Among 36 MOAAS, the BUDR LI was less than 1% in 77% of enhanced tumors and 61% of unenhanced tumors. Among 35 HAAS, it was less than 5% in 56% of enhanced tumors and 90% of unenhanced tumors. Therefore, contrast enhancement on CT scans does not always correctly predict proliferative potential in these tumors, and biopsy and labeling studies are recommended before therapy.

Adolescent↗
PubMed1990

Polyamine accumulation and vasogenic oedema in the genesis of late delayed radiation injury of the central nervous system (CNS).

Polyamine (PA) accumulation has been associated with blood-brain barrier (BBB) disruption and vasogenic oedema after cold injury. PAs and water content were measured in a rat spinal cord model of late-delayed radiation injury and were found to be elevated at paralysis. The elevated PA levels could be significantly reduced by treatment with difluoromethylornithine (DFMO). In unirradiated rats DFMO reduced putrescine to undetectable levels after 10-12 weeks. These data suggest that blockade of PA synthesis may be useful in treating the vasogenic oedema of radiation injury and may improve CNS radiation tolerance.

Animals↗
PubMed1990

Combined frontotemporal-orbitozygomatic approach for tumors of the sphenoid wing and orbit.

An extension of a combined frontotemporal and orbitozygomatic exposure was developed to remove 8 hyperostosing invasive sphenoid wing meningiomas (Group 1) and 11 complicated intraorbital tumors with and without intracranial extension (Group 2). Two separate bone flaps were created: a free frontotemporal-sphenoidal (pterional) bone flap and en bloc removal of the superior and lateral orbital margins with attached zygomatic arch. Cranio-orbital reconstruction was performed using the inner table of the pterional bone flap. Complete tumor removal was achieved in 14 patients and near total removal in 5. There was no mortality and in those patients who did not require orbital exenteration excellent to good cosmetic results were achieved in all but one case. This approach affords a wide exposure of the orbit and anterior and middle skull base, so that large tumors of the orbit and tumors involving the orbital apex, sphenoid wing, and infratemporal and pterygopalatine fossae can be removed.

Adolescent↗
PubMed1990

Interstitial brachytherapy.

In the last several years there has been a renewed interest in interstitial brachytherapy for the treatment of both newly diagnosed and recurrent malignant gliomas and solitary cerebral metastases. A variety of techniques are currently in use for the planning and stereotactic implantation of radioactive isotopes into these tumors. Although there seems to be strong evidence to support the use of this technique for recurrent malignant gliomas, further work is needed to confirm its efficacy in an adjuvant setting for treating of newly diagnosed tumors and to determine the effect of the addition of hyperthermia or chemotherapy on outcome.

Brachytherapy↗
PubMed1989

Keyhole craniectomy for correction of sagittal synostosis.

A modification of the technique combining sagittal strip, circular occipital and biparietal wedge craniectomies (Albright's procedure) for the treatment of sagittal synostosis, with prominent occipital bossing, is described. "Keyhole," as opposed to wedge, parietal craniectomies allow improvement in the shape of the skull, beginning intraoperatively, while eliminating the outbending of the parietal bone that occurs at the apex of a wedge craniectomy.

Cranial Sutures↗
PubMed1989

Temporary vessel occlusion and barbiturate protection in cerebral aneurysm surgery.

In a review of 147 patients with intracranial aneurysms surgically treated by one surgeon (FAD) between 1980 and 1987, 36 selected patients received intraoperative barbiturate protection with sodium thiopental during temporary arterial occlusion. Thiopental doses of 5 to 15 mg/kg were used. Twenty-nine of 36 (81%) had ruptured aneurysms. Occlusion times ranged from 3 to 93 minutes, with a mean of 16.2 minutes. Seven patients had new neurological deficit in the immediate postoperative period, but in only two did these persist. Twenty-one patients (72%) with subarachnoid hemorrhage and 6 with incidental aneurysms made a good recovery. Of the 9 patients with significant permanent deficit, all but 2 were related to either the severity of the initial hemorrhage or to delayed vasospasm. In only one instance might temporary arterial occlusion have led to permanent neurological sequelae. Temporary arterial occlusion with barbiturate protection is a safe technique. For aneurysms that are more surgically complex, it allows for complete dissection of the aneurysm neck and identification and preservation of the surrounding vascular anatomy, while reducing the risk of intraoperative rupture and postoperative stroke.

Adult↗
PubMed1988

Lymphocytic adenohypophysitis.

Lymphocytic adenohypophysitis (LAH) is an uncommon disorder in the spectrum of pituitary disease. Twenty-three cases proven by biopsy or at autopsy have been reported since 1962. We report 2 further cases and review the etiology, immunology and pathology of the disease. The diagnosis should be considered in a female patient who presents during the post-partum period with the clinical picture of a non-functional or prolactin cell pituitary adenoma and evidence of hypopituitarism.

Adult↗
PubMed1985

Acalculous cholecystitis: its role as a complication of major burn injury.

The authors present four cases of acute acalculous cholecystitis complicating major burn injury and review the recent literature on acalculous cholecystitis. All patients were men and ranged in age from 22 to 40 years. The mean extent of the burn was 50% of the total body surface area, with an average 29% third-degree component. All four patients survived. Because of their severity, major burn injuries expose patients to many risks, including acute acalculous cholecystitis. Recent experimental evidence supports a vascular insult through the activation of Factor XII pathways as the initial event. A diagnosis is made on clinical grounds, supported by laboratory and ultrasonographic findings, in a patient with a burn covering more than 30% of the total body surface area and who has signs of acute cholecystitis. Cholecystectomy is the treatment of choice; tube cholecystostomy is reserved for critically ill patients.

Acute Disease↗
PubMedDate not supplied

Thickened pituitary stalk on MR images in patients with diabetes insipidus and Langerhans cell histiocytosis.

The MR images of four female patients with acute onset of central diabetes insipidus and pathologically confirmed Langerhans cell histiocytosis were evaluated retrospectively for evidence of lesions in the hypothalamic-pituitary axis. The examinations were conducted on a 1.5-T MR system with thin-section sagittal and coronal T1-weighted (short TR/short TE) and T2-weighted (long TR/long TE) images. Three patients underwent T1-weighted MR after IV administration of gadopentetate dimeglumine. Compared with 20 normal subjects who were evaluated with the same MR protocol, three of the four patients had a symmetrically thickened pituitary stalk that demonstrated homogeneous signal enhancement following contrast administration. The high signal intensity of the posterior lobe, which was seen in normal subjects on T1-weighted sagittal images, was absent in all four patients. Two patients had associated abnormalities on either chest films or imaging studies of the temporal bone and two patients had isolated CNS Langerhans cell histiocytosis. The combination of a thickened pituitary stalk and absent posterior pituitary hyperintensity, while nonspecific for Langerhans cell histiocytosis, should nevertheless prompt further studies, such as chest films, bone scanning, or temporal bone CT, to attempt to narrow the differential diagnosis. Gadopentetate dimeglumine, in particular, may be a useful adjunct in the MR examination of the patient with diabetes insipidus.

Adolescent↗